mm: migrate: remove folio_migrate_copy()

The folio_migrate_copy() is just a wrapper of folio_copy() and
folio_migrate_flags(), it is simple and only aio use it for now, unfold it
and remove folio_migrate_copy().

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Kefeng Wang <[e-mail]>
Reviewed-by: Jane Chu <[e-mail]>
Cc: Alistair Popple <[e-mail]>
Cc: Benjamin LaHaise <[e-mail]>
Cc: David Hildenbrand <[e-mail]>
Cc: Hugh Dickins <[e-mail]>
Cc: Jérôme Glisse <[e-mail]>
Cc: Jiaqi Yan <[e-mail]>
Cc: Lance Yang <[e-mail]>
Cc: Matthew Wilcox (Oracle) <[e-mail]>
Cc: Miaohe Lin <[e-mail]>
Cc: Muchun Song <[e-mail]>
Cc: Naoya Horiguchi <[e-mail]>
Cc: Oscar Salvador <[e-mail]>
Cc: Tony Luck <[e-mail]>
Cc: Vishal Moola (Oracle) <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

fs/aio.c

···
 	 * events from being lost.
 	 */
 	spin_lock_irqsave(&ctx->completion_lock, flags);
-	folio_migrate_copy(dst, src);
+	folio_copy(dst, src);
+	folio_migrate_flags(dst, src);
 	BUG_ON(ctx->ring_folios[idx] != src);
 	ctx->ring_folios[idx] = dst;
 	spin_unlock_irqrestore(&ctx->completion_lock, flags);

include/linux/migrate.h

···
 void migration_entry_wait_on_locked(swp_entry_t entry, spinlock_t *ptl)
 		__releases(ptl);
 void folio_migrate_flags(struct folio *newfolio, struct folio *folio);
-void folio_migrate_copy(struct folio *newfolio, struct folio *folio);
 int folio_migrate_mapping(struct address_space *mapping,
 		struct folio *newfolio, struct folio *folio, int extra_count);
 

mm/migrate.c

···
 }
 EXPORT_SYMBOL(folio_migrate_flags);
 
-void folio_migrate_copy(struct folio *newfolio, struct folio *folio)
-{
-	folio_copy(newfolio, folio);
-	folio_migrate_flags(newfolio, folio);
-}
-EXPORT_SYMBOL(folio_migrate_copy);
-
 /************************************************************
  *                    Migration functions
  ***********************************************************/